In "The Wife of Bath's Tale," why does the Wife of Bath want to show the Knight changing?
There is a pleasing genius in the way that this tale is structured. Let us remember that the knight first has to find the answer to what women desire most, and then, thanks to his marriage to the old crone who gave him that answer, he has to realise for himself the truth of the answer that he gave the Queen. It is as if the knight comes to know in his head first that women desire to have mastery, and then is forced to realise it in his heart. This of course supports and cements the Wife of Bath's purpose in presenting us with a man who comes to realise that he is better off leaving his wife with mastery, then gains perfect happiness as a result. Note the knight's response when his answer to his wife, telling her to make the choice for him, gives him exactly what he wants and desires:
He caught her up in both his arms for joy,
With his whole heart bathed in a bath of bliss;
They kiss; a thousand times they kiss.
And she obeyed him in all things that might
Afford him satisfaction or delight.
When the knight realises that by giving his wife mastery he gets what he wants, he comes to be precisely the kind of man that the Wife is looking for and represents what men should be like in her opinion. Showing his journey to this point cements her argument and reinforces it.